Transcript cryptosporidiosis - Bugando Medical Centre

CRYPTOSPORIDIOSIS
OPPORTUNISTIC INFECTION
PREPARED BY
Gerald Anthon Chuwa
Head Parasitology section BMC.
Introduction
• Cryptosporidium infection (cryptosporidiosis)
is a gastrointestinal disease whose primary
symptom is diarrhea.
• The illness begins when the tiny
cryptosporidium parasites enter your
body and travel to your small intestine.
• Cryptosporidium then begins its life cycle
inside your body — burrowing into the walls
of your intestines and then later infective
oocysts being shed in your feces.
• In most healthy people, a cryptosporidium
infection produces a bout of watery diarrhea
and the infection usually goes away within a
week or two.
• In a patient with a compromised immune
system, a cryptosporidium infection can
become life-threatening without proper
treatment.
• You can help prevent cryptosporidium by
practicing good hygiene and by avoiding
drinking water that hasn't been boiled or
filtered.
MORPHOLOGY
• Cryptosporidium species are able to infect and
reproduce in the epithelial cell lining of the GI
and respiratory tracts without causing
cytopathic effects.
HISTORY
• This protozoan parasite was first described by
Ernest Edward Tyzzer an American
parasitologist in 1912.
• Many outbreaks were associated with
municipal water supplies and in swimming
pools.
• C hominis and C parvum cause most human
infections. In immunocompeten t individuals,
the organisms are primarily localized to the
distal small intestines, whereas in
immunocompromised hosts, the parasites
have been identified throughout the gut,
biliary tract, and respiratory tract.
• Transmission
• The disease is transmitted via the fecal-oral
route from infected hosts. Most sporadic
infections occur through person-to-person
contact.
• Nonetheless, transmission can also occur
following animal contact, ingestion of water
(mainly during swimming), or through food.
Extensive waterborne outbreaks have resulted
from contamination of municipal water and
recreational waters (eg, swimming pools,
ponds, lakes).
• Cryptosporidium has emerged as the most
frequently recognized cause of recreational
water–associated outbreaks of gastroenteritis,
particularly in treated (disinfected) venues.
• This is because in the oocyst stage of its life
cycle, Cryptosporidium can resist disinfection,
including chlorination, and can survive for a
prolonged period in the environment
Cryptosporidium oocysts stained by
modified Zn stain.
Mature oocyst containing two sporocysts each
with 4sporozoites
LIFE CYCLE
• Life cycle
• Cryptosporidium does not multiply outside of
the host. Cryptosporidium can complete its life
cycle within a single host, including its asexual
(merogony) and sexual (sporogony)
reproductive cycles.
• Infection is initiated by ingestion of oocysts,
which are activated in the stomach and upper
intestines to release 4 infective sporozoites
(see the first image below). These motile
sporozoites bind to the receptors on the
surface of the intestinal epithelial cells and
are ingested into a parasitophorous vacuole
near the surface of the epithelial cell,
separated from the cytoplasm by a dense
layer.
• Once inside the epithelial cell, the parasite
goes through a series of sexual and asexual
multiplication steps leading to the production
of oocysts. Two morphologic forms of the
oocysts have been described:
• thin-walled oocysts (asexual stage) excyst
within the same host (causing self-infection),
whereas the thick-walled oocysts (sexual
stage) are shed into the environment. Oocyst
shedding can continue for weeks after a
patient experiences clinical improvement.
Diagrammatic representation of life
cycle of cryptosporidium.
Symptoms
 The first signs and symptoms usually appear two
to seven days after infection with
cryptosporidium and may include:
 Watery diarrhea
 Dehydration
 Weight loss
 Stomach cramps or pain
 Fever
 Nausea
 Vomiting
• Symptoms may last for up to two weeks,
though they may come and go sporadically for
up to a month, even in people with healthy
immune systems. Some people with
cryptosporidium infection may have no
symptoms
Causes
• Cryptosporidium infection begins when you
ingest the cells of one of nearly a dozen
species of the one-celled cryptosporidium
parasite. The Cryptosporidium parvum (C.
parvum) species is responsible for the
majority of infections in humans.
• These parasites then travel to your intestinal
tract, where they settle into the walls of your
intestines. Eventually, more cells are produced
and shed in massive quantities into your feces,
where they are highly contagious
• You can become infected with
cryptosporidium by touching anything that
has come in contact with contaminated feces.
Methods of infection include:
• Swallowing or putting something
contaminated with cryptosporidium into your
mouth
• Drinking water contaminated with
cryptosporidium
• Swimming in water contaminated with
cryptosporidium and accidentally swallowing
some of it Eating uncooked food
contaminated with cryptosporidium Touching
your hand to your mouth if your hand has
been in contact with a contaminated surface
or object Having close contact with other
infected people or animals — especially their
feces — which can allow the parasite to be
transmitted from your hands to your mouth
• If you have a compromised immune system
from HIV/AIDS, you're more susceptible to
illness from cryptosporidium than is a person
with a healthy immune system. People with
HIV/AIDS can develop severe symptoms and a
chronic, persistent form of disease that may
be difficult to treat
• Cryptosporidium is one of the most common
causes of diarrhea in humans. This parasite is
difficult to eradicate because it's resistant to
many chlorine-based disinfectants and can't
be effectively removed by many filters.
Cryptosporidium can also survive in the
environment for many months at varying
temperatures, though the parasite can be
destroyed by freezing or boiling.
Risk factors
• People who are at increased risk of developing
cryptosporidiosis include:
• Those who are exposed to contaminated
water
• Children, particularly those wearing diapers,
who attend child care centers
• Parents of infected children
• Child care workers Animal handlers Those who
engage in oral-to-anal sexual activity
International travelers, especially those
traveling to developing countries Backpackers,
hikers and campers who drink untreated,
unfiltered wate
• Swimmers who swallow water in pools, lakes
and rivers People who drink water from
shallow, unprotected wells
Complications
Complications of cryptosporidium infection
include:
• Malnutrition resulting from poor absorption
of nutrients from your intestinal tract
(malabsorption)
• Severe dehydration
• Significant weight loss (wasting)
• Inflammation of a bile duct — the passage
between your liver, gallbladder and small
intestine
• Inflammation of your gallbladder, liver or
pancreas
• Cryptosporidium infection itself isn't lifethreatening. However, if you've had a transplant
or if you have a weakened immune system,
developing complications can be dangerous.
DIAGNOSIS
• You may undergo the following tests to diagnose
cryptosporidium infection:
• Acid-staining test. The simplest way to diagnose
cryptosporidium infection is a method called an
acid-staining test, which identifies
cryptosporidium under a microscope. To obtain
cells for the analysis, your doctor might ask for a
stool sample, or in more extreme cases, take a
tissue sample (biopsy) from your intestine for the
test
Modified Ziehl Neelsen stain
• Make a faecal smear from suspected material
in normal saline.
• Allow the smear to dry
• Fix the smear in methyl alcohol for 15
minutes.
• Stain the smear with carbol fuchsin for 15
minutes
• Decolourise with 1% acid alcohol to remove
excess stain.
• Counterstain with methylene blue for 30
seconds
• Dry the film and examine using the high
power objective.
• Other tests. Once it's clear that your infection
is cryptosporidium, you may need further
testing to check for development of serious
complications. For example, checking liver and
gallbladder function may determine whether
the infection has spread.
C. parvum - Cysts in stool Acid fast
• If you have both AIDS and cryptosporidiosis, a
T cell count — which measures the level of a
certain white blood cell that's part of your
immune system — can help predict the
duration of the cryptosporidiosis. A high T cell
count means you're more likely to recover
quickly, while a low count means you may
need to be monitored for further
complications.
Treatment
• There's no commonly advised specific
treatment for cryptosporidiosis, and recovery
usually depends on the health of your
immune system. Most healthy people recover
within two weeks without medical attention.
• If you have a compromised immune system,
the illness can last and lead to significant
malnutrition and wasting. The goal of
treatment is to alleviate symptoms and
improve your immune response.
Cryptosporidium treatment options include
• Anti-parasitic drugs. Medications such as
nitazoxanide (Alinia) can help alleviate
diarrhea by attacking the metabolic processes
of the cryptosporidium organisms.
Azithromycin (Zithromax) may be given along
with one of these medications in people with
compromised immune systems
• Anti-motility agents. These medications slow
down the movements of your intestines and
increase fluid absorption to relieve diarrhea
and restore normal stools. Anti-motility drugs
include loperamide and its derivatives
(Imodium A-D, others). Talk with your doctor
before taking any of these medications.
• Fluid replacement. You'll need oral or
intravenous replacement of fluids and
electrolytes — minerals such as sodium,
potassium and calcium that maintain the
balance of fluids in your body — lost to
persistent diarrhea. These precautions will
help keep your body hydrated and functioning
properly.
• Anti-retroviral therapies. If you have
HIV/AIDS, highly active anti-retroviral therapy
(HAART) can reduce the viral load in your body
and boost your immune response. Restoring
your immune system to a certain level may
completely resolve symptoms of
cryptosporidiosis.
Prevention and control.
• Cryptosporidium infection is contagious, so take
precautions to avoid spreading the parasite to
other people.
• All preventive methods aim to reduce or prevent
the transmission of the cryptosporidium germs
that are shed in human and animal feces.
Precautions are especially important for people
with compromised immune systems. Follow
these suggestions
• Practice good hygiene. Wash your hands with
soap and water after using the toilet, changing
diapers, and before and after eating.
Thoroughly wash all fruits and vegetables that
you will eat raw, and avoid eating any food
you suspect might be contaminated.
• Purify drinking water if you have a weakened
immune system or are traveling in an area
with a high risk of infection. Methods include
boiling — at least one minute at a rolling boil
— or filtering, although filtering may not be as
effective as
• boiling. Limit swimming activities in lakes,
streams and public swimming pools, especially
if the water is likely to be contaminated or if
you have a compromised immune system.
Avoid fecal exposure during sexual activity
• Avoid fecal exposure during sexual activity.
• Handle newborn farm and domestic animals
with care. Be sure to wash your hands after
handling the animals.
• Always refrain from swimming anytime you're
experiencing diarrhea. If you know you've had
a cryptosporidium infection, don't go
swimming for at least two weeks after your
symptoms subside because you may still be
contagious
Situation at BMC
No scientific study has been conducted to
understand the morbidity and mortality.
Specimens from suspected cases are sent to
laboratory for modified Zn stain to
demonstrate the parasites.
As from January to May 2014 the laboratory
received 12 faecal specimens for modified Zn
stain an average of 2 samples per month.
• Out of 12 received samples 4 were positive
and 8 were negative.